Known in the prior art is a device for destruction of rocks by expensive forces (SU, A, No. 691,564) the power actuator of which comprises a casing filled with a working medium, for example, water and is made up of two portions the walls of one of which are provided with perforations in the form of grooves, and an enclosure disposed on one of the casing portions and adapted to be moved onto the other portion of the casing. Recesses of the load-bearing casing internally accommodate wedge-shaped elastic expanding elements. After the enclosure is installed on that portion of the casing which is made with perforations, it is filled with a refrigerating agent, for example, carbon dioxide. The working medium disposed in this portion of the casing is subjected to freezing. After the enclosure is shifted onto the other portion of the casing the working medium is frozen in this portion to a temperature of -25.degree. C. and down. After the device is introduced in a blasthole of the monolith to be destroyed the working medium temperature is brought up to -14.degree. C. and upward at which it becomes fluid. Passing under a pressure in the grooves made in the walls of the casing the working medium acts on the wedge-shaped elastic expanding elements which exert pressure on the blasthole wall, thereby destroying the monolith.
The power actuator of the given design fails to develop sufficiently great expansive forces and is not convenient in operation because of the movable enclosure due to which the field of its application is limited.
Also known in the prior art is a power actuator (SU, A No. 810,340) operating at the expense of energy of an expanding working medium and comprising a load-bearing casing filled with the working medium and arranged along the longitudinal axis of a multi-section enclosure, The enclosure is separated by rigid transverse partitions into sections communicated with one another by means of connections through which the enclosure sections are supplied with a heat-transfer agent, for example, hot water at a temperature of 80.degree.-90.degree. C. for heating the working medium, for example, a mixture containing 50% of paraffin and 50% of stearin, or cold water water at a temperature of 10.degree. C. for cooling the working medium.
One end of the load-bearing casing is made blind and its opposite end is connected with an actuating member, for example, with a perforating press. The section-by-section filling of the enclosure with the heat-transfer agent insures the step-by-step expansion of the working medium which makes it possible to regulate the forces transmitted to the actuating member by way of gradually heating the load-bearing casing.
The pressure exerted on the actuating member and consequently the travel of the actuating member working tool are defined by the amount of the working medium increased in volume due to expansion. In order to obtain in the power actuator of the known design an additional force to be transmitted to the actuating member, it is necessary to increase the mass of the working medium and, consequently, to enlarge the overall dimensions of the load-bearing casing and hence of the enclosure which reduces the efficiency of the power actuator operation.